The disclosure relates to a capacitor, and to a substrate module in which the capacitor is mounted on a substrate.
In order to reduce a noise that occurs in a power supply, it may be necessary to couple together capacitors having different capacities and different self-resonant frequencies between a direct current (DC) power supply layer and a ground layer, and to keep impedance low at a wideband frequency.
In a case of using the capacitors having different self-resonant frequencies, however, an antiresonance phenomenon occurs among the capacitors, thus causing a phenomenon in which impedance of the power supply layer is increased. As a means to suppress the phenomena, it has been proposed to use a capacitor having large equivalent series resistance (ESR). For example, reference is made to Japanese Unexamined Patent Application Publications No. 2003-168620, No. 2009-60114, and No. 2010-45323.